Milankovitch Flashcards
what varies the energy received at the TOP OF THE ATMOSPHERE
if the motion of the Earth relatives to the sun is NOT CONSTANT
what did the 3 variations in the Earth’s orbit result in
a 5% variation in the energy received
where is the 5% variation in energy received very noticeable
at high latitudes
the three variations in the Earth’s orbit
- eccentricity of the orbit (stretch)
- change in the tilt of the axis of rotation (roll)
- precession of the equinoxes (wobble)
stretch AKA
Eccentricity of the orbit
what variation in the Earth’s orbit is this
90 000 year cycle
The eccentricity of the orbit (stretch)
The eccentricity of the orbit (stretch)
orbit changes from nearly circular to more elliptical
in the eccentricity of the orbit (stretch), what is associated with a more circular orbit
a constant amount of radiation received through the year
The eccentricity of the orbit (stretch), what is associated with a more elliptical orbit
more variation in the sunshine received
what does greater eccentricity cause in terms of hemispheres
greater seasonality in ONE hemisphere and REDUCED in the other
what variation of Earth’s orbit is this
41 000 year cycle
change in the tilt of the axis of rotation
what variation of Earth’s orbit is this
22 000 year cycle
Precession of the equinoxes (wobble)
present tilt of axis rotation
23.4 degrees
the change in the tilt of the axis of rotation varies from
22 degrees to 24.4 degrees
greater tilt causes in regards to hemisphers
greater seasonality in BOTH hemispheres
no tilt would mean _____
no seasons
what happens to the arctic circle with an increased axial tilt
it increases and there is more seasonality
when the tilt is decreased polar regions receive _____ sunlight
less
when tilt is increased, polar regions received ____ sunlight
more
precession of the equinoxes
affects the timing of aphelion and perihelion relative to the seasons
earth is closest to sun _____ and farthest ____
Jan 3 and July 4
precession of the equinoxes and how it affects the hemispheres
NH
winters are milder and summers cooler
SH
winters are colder and summers warmer
according to the precession of the equinoxes, there is _____ seasonality in the SH
more
according to the precession of the equinoxes, there is _____ seasonality in the NH
less
Precession of the equinoxes affects the two hemispheres _____ (the same or different)
differently
what was true 10 000 years ago in regards to the farthest and closest to the sun
it was reversed, July was the closest earth was to the sun
what can the 3 orbital cycles explain
the overall pattern of warming and cooling
what can the 3 orbitals NOT explain
the speed of onset and end of glacial periods
true or false
there must be internal feedback mechs to amplify the external orbital changes
true
what is the range of eccentricity
20%
what does the precession of the equinoxes work with to determine which hemisphere has more seasonality and which has less
eccentricity
Milankovitch theory results in
a 96 000 year climatic cycle through changes in the insolation
